Antiknocking motor fuel



Patented Jan. 12, 1937 PATENT OFFICE ANTIKNOCKING MOTOR FUEL JosefMartin Michel, Bitterfeld, Germany, assignor to I. G. FarbenindnstrieAktiengesellschaft, Frankfort-on-the-Main, Germany N 0 Drawing.

Application June 1, 1934, Serial No. 728,627. In Germany June 14, 1933 6Claims.

This invention relates to improvements in antiknocking motor fuels, andmore particularly to a process for stabilizing tetra-ethyl-lead whenused as an antiknock agent.

The antiknock compounds recently used in motor fuels and containingtetra-ethyl-lead as the active component, if desired together with otherorganic substances, possess the undesirable property of decomposing,especially under the influence of light and in the presence of water;they are even decomposed by light alone, in the complete absence ofwater, although somewhat more slowly. Apart from the ineffectiveness ofsuch decomposed compounds for the purpose in view, the decompositionproducts which separate out in the form of a mud, strongly corrode someof the metals employed for constructing the fuel receptacle, suchcorrosion being especially dangerous, since it is apt to manifest itselfby a strongly intensified local attack. These phenomena are moreoverpromoted by the presence of even but a small percentage of water in thefuels which, as a rule, cannot be avoided.

Exhaustive research upon which the present invention is based has shownthat it is possible to stabilize the tetra-ethyl-lead as against theinfluence of light and/or water, to a very high degree by adding theretovery small proportions of water-soluble fluorides. In this manner,corrosion in the dark is practically completely avoided and isdiminished even in the light to a very considerable extent.

The present invention accordingly comprises adding extremely smallamounts of fluorides (a' few hundredths of 1 percent) to the antiknockcompounds or the fuels containing the latter, the result being thatantiknock compounds thus treated retain their effectiveness even whenthe fuels containing same have been subjected to prolonged storage. Bythus preventing the antiknock compounds from decomposing, corrosion ofthe metallic fuel receptacles is avoided, no matter whether moisture bepresent or not.

Neutral ammonium fluoride has been found suitable for the purpose of thepresent invention, since owing to its volatility, deposits are notliable to form in the engine during consumption of the fuels treatedtherewith. Proportions of ammonium fluoride ranging from 0.01 to 0.05percent calculated on the amount of fuel to be stabilized, have beenfound particularly suitable. While this fluoride may be successfullyemployed, it is frequently more advantageous to employ sodium orpotassium fluoride in approximately the same percentages as abovestated, in view of the fact that ammonium fluoride is capable ofcorroding some metals to a certain extent.

In order to avoid undissoived salt from gaining access to the feed pipesfor the fuel or into the motor respectively, the fluoride may beintroduced into the fuel receptacle in a perforated cartridge, which ismounted on the inner walls of said receptacle.

I claim:-

1. An anti-knock agent comprising tetraethyl lead and a small amount ofa water-soluble fluoride to stabilize the tetraethyl lead against lightand water.

2. An anti-knock agent comprising tetraethyl lead and a small amount ofan alkali metal fluoride to stabilize the tetraethyl lead against lightand water.

3. A motor fuel non-corrosive to metallic containers on long standingcomprising tetraethyl lead and a small amount of a water-solublefluoride.

4. A motor fuel non-corrosive to metallic containers on long standingcomprising tetraethyl lead and a small amount of an alkali metalfluoride.

5. A method of stabilizing motor fuels containing tetraethyl lead whichcomprises acroixing therewith a small quantity of a water-sorzblefluoride to stabilize the tetraethyl lead against light and water.

6. A method of stabilizing motor fuels containing tetraethyl lead whichcomprises admixing therewith a small quantity of an alkali metalfluoride to stabilize the tetraethyl lead against light and water.

J OSEF MARTIN MICHEL.

